In Situ Formation of Silicon Carbide Nanofibers on Cordierite Substrates

Twenty-five years of diesel particulate filter (DPF) developments have shown that high-volume ceramic materials are well suited for the harsh requirements of exhaust after treatment. Nevertheless, problems regarding filter reliability and durability associated with the regeneration of the filter have limited their serious application until only recently. To extend useful filter life, the present study has examined the growth of silicon carbide (SiC) nanofibers by a simple carbothermal reduction process on cordierite support surfaces using cheap raw materials such as kaolin, talc, and carbon black. Transmission electron microscopy confirms the crystalline (β - SiC) nature of the nanofibers (10–20 nm diameter). The growth of these nanofibers increases the support-specific surface area restricting the agglomeration of noble metal catalyst particles that otherwise occurs in wash-coat sintering. As a result, fewer particles are needed to perform the catalyst role (at reduced cost) and the support structure can host the catalyst for prolonged times at higher temperatures. As the future will see increasing economic competition in filter fabrication routes and materials, this new design of catalytic DPF promises to play a significant role.